Carbonyl Halides of the Group 6 Transition Metals. XXVIII. Phosphorus-31 and Selenium-77 N.M.R. Studies of Some Selenium-Group 15 Donor Complexes

1987 ◽  
Vol 40 (1) ◽  
pp. 13 ◽  
Author(s):  
R Colton ◽  
P Panagiotidou
Keyword(s):  
Transition Metals ◽  
Silver Nitrate ◽  
The Other ◽  
Donor Atom ◽  
Monodentate Ligand ◽  
Quantitative Formation ◽  
Other Hand ◽  
Group 6 ◽  
Group 15

The ligands Ph2PCH2P(Se)Ph2 ( dpmSe ) and Ph2AsCH2CH2P(Se)Ph2 ( apeSe ) have been treated with Group 6 metal pentacarbonyl halo anions, [M(C0)5X]-, the Group 6 hexacarbonyls and the carbonyl halides M(C0)4X2 (M = Mo, W, X = C1, Br). Reaction of both dpmSe and apeSe with the anions [M(C0)5X]- in the presence of silver nitrate gave the complexes M(CO)5(L-L′) (L-L′ = dpmSe or apeSe ) with the ligand coordinated in a monodentate fashion through the Group 15 donor atom. Reaction of dpmSe with the hexacarbonyls gave only M(C0)4( dpmSe ) with the ligand chelated but, in contrast, apeSe could not be chelated to metal(0) and acted only as a monodentate ligand. These differences are rationalized in terms of the structure of the ligands. The behaviour of the ligands is much more similar in the metal(11) carbonyl halide chemistry. Both formed a mixture of two isomers of M(CO)3(L-L′)X2 (L-L′= dpmSe, apeSe ) in which the ligands are chelated . In the apeSe system, n.m.r. studies show these isomers are in an equilibrium which varies with temperature at a rate which is slow on the n.m.r. timescale, but the dpmSe complexes do not interchange. On reaction with further ligand, only one of the isomers of M(CO)3( dpmSe )X2 reacts to give incomplete formation of the dicarbonyl Mo(Co)2( dpmSe )2X2, which has one dpmSe ligand chelated and the other monodentate through phosphorus. On the other hand, for the apeSe system quantitative formation of Mo(CO)2( apeSe )2X2 was observed. For the apeSe system only, bubbling CO through a solution of M(CO)2( apeSe )2X2 gave M(CO)3( apeSe )2X2 with the ligands monodentate through arsenic. Extensive 31P and 77Se n.m.r. studies are described.

Carbonyl halides of the Group 6 transition metals. VI. Complexes with Bis(diphenylphosphino)methane

1968 ◽  
Vol 21 (5) ◽  
pp. 1143 ◽  
Author(s):  
MW Anker ◽  
R Colton ◽  
IB Tomkins
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transition Metals ◽  
Monodentate Ligand ◽  
Monomeric Complex ◽  
Group 6 ◽  
Nuclear Magnetic

Complexes of the type MX2(CO)2 diphos2 [M = Mo, W; X = Cl, Br; diphos = bis(diphenylphosphino)methane] have been prepared and characterized. The complexes are neutral, diamagnetic, seven-coordinate species with one of the diphosphine molecules acting as a monodentate ligand. Nuclear magnetic resonance, conductance, and molecular weight studies support this view. The monomeric complex MoBr2(CO)3 diphos has also been prepared.

Gettering Mechanism of Cu in Silicon Calculated from First Principles

2005 ◽  
Vol 108-109 ◽  
pp. 115-124 ◽  
Author(s):  
Kazuhito Matsukawa ◽  
Nobusuke Hattori ◽  
Shigeto Maegawa ◽  
Koun Shirai ◽  
Hiroshi Katayama-Yoshida
Keyword(s):  
Molecular Dynamics ◽  
Binding Energy ◽  
Transition Metals ◽  
First Principles ◽  
Negative Charge ◽  
Positive Charge ◽  
Binding Energies ◽  
The Other ◽  
Other Hand ◽  
Dynamics Method

The binding energy between 3d transition metals (TM) such as iron (Fe), nickel (Ni) and copper (Cu), and boron (B) in Si are studied using first-principles molecular dynamics method. The binding energies of between each TM for Fe, Ni, Cu and B are 0.64,0.57,and 0.44eV respectively, and the binding energy of Fe and B is the largest, on the other hand, binding energy of Ni and B is the smallest. This result is well in agreement with the experiment fact that Fe and Cu exist as a positive charge in P+ silicon, so it is easy to combine with the B, which has a negative charge, on the other hand, Ni exists in the state of neutrality electrically in P+ silicon, so it can not combine with B atom.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

ON THE OTHER HAND

1961 ◽  
Vol 6 (6) ◽  
pp. 222-223
Author(s):  
Edwin G. Boring
Keyword(s):  
The Other ◽  
Other Hand
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